Challenge

Challenge

Topics: Loops, Dictionaries, Conditionals, Lists, Strings

Task: Create a Python script that takes input from a user and creates a configuration snippet. Optionally connect to a network device and get more information.

Background

Your customer has asked you to create a Python script that generates a configuration snippet based on user input. The script should prompt the user for the following information:

1. Device hostname
2. Device IP address
3. Device model
4. Access VLAN id

The snippet should either collect interface information using Netmiko or prompt the user for the following information:

1. Interface name(s)

The script should then generate a configuration snippet that includes the device hostname, IP address, model, and interface information. The snippet should be printed to the screen.

Example Output

hostname R1
!
interface Loopback0
  ip address 10.9.8.7 255.255.255.255
  no shutdown
!
interface GigabitEthernet0/0
  switchport mode access
  switchport access vlan 20
  no shutdown
!
[... more access interfaces ...]

Solution / Inspiration

We realise things are getting trickier and hence a suggested implementation is provided already.

We are now combining multiple concepts into a single challenge. This is a common scenario in programming where you need to combine different concepts to solve a problem.

If you have the guts, attempt the challenge on your own. However, if you get stuck or need some guidance or inspiration, a suggested solution is provided below.

You can always improve upon the solution provided with your own ideas with a slight twist of the problem statement.

Click here to see the solution

import netmiko
from getpass import getpass

# Prompt the user for device information
hostname = input("Enter the device hostname: ")
ip = input("Enter the device IP address: ")

# Create a dictionary to store device information
device = {
    "hostname": hostname,
    "ip": ip,
    "model": input("Enter the device model (default: cisco_ios): "),
    "vlan": input("Enter the access VLAN ID: "),
}

# If the user does not provide a model, use the default value
if not device.get("model"):
    device["model"] = "cisco_ios"

# Let the user provide a comma-separated list of interfaces
interfaces = input("Enter the interface name(s) (comma-separated) (press enter to collect): ")

# If the user does not provide any interfaces, use Netmiko to get more information
if not interfaces:
    # Connect to the device and get more information
    user = input("Enter your username: ")
    password = getpass("Enter your password: ")

    handler = netmiko.ConnectHandler(
        device_type=device["model"],
        username=user,
        password=password,
        host=device["ip"],
    )

    output = handler.send_command("show ip interface brief", use_textfsm=True)
    interfaces = []
    for interface in output:
        interface_name = interface["interface"]
        interfaces.append(interface_name)
else:
    interfaces = interfaces.split(",")

# define a template, we will later use .format() to fill in the values
interface_template = """!
interface {name}
  switchport mode access
  switchport access vlan {vlan_id}
  no shutdown
"""

# Create a configuration snippet
config = f"""
hostname {device['hostname']}
!
interface Loopback0
  ip address {device['ip']} 255.255.255.255
  no shutdown
!
"""

for interface_name in interfaces:
    # Create an interface configuration snippet using the template
    interface_config = interface_template.format(name = interface_name, vlan_id=device["vlan"])
    # extend the configuration snippet with interface information
    config += interface_config

print(config)